Heretofore in the use of chemical solution circulators which normally include a tank, a pump with an intake connected to the tank and a discharge pipe for delivering solution to an enclosure communicating with the tank, concentration of the chemicals within the solution is gradually depleted by carryout and makeup water added to the tank. Heretofore it was necessary to shut down the circulator and provide for the addition of such sufficient quantities of concentrated chemical into th solution and to test the solution to bring it up to a predetermined concentration for a particular washing or rinsing problem. Heretofore additive chemicals have been wasted and there has been considerable time delay is shutting down a circulating system for the purpose of adding chemicals to return the solution to a predetermined chemical concentration. Heretofore it has been recognized that in order to maintain uniform chemical concentrations and for providing improved and uniform cleaning or washing chemical concentration control is needed by someone for maintaining of health and safety factors involved in the manual dispensing of chemical additives. Efforts have been made to do this automatically.